Validation of Stability for an Induction Machine Drive Using Experiments 1

Abstract The objective of this contribution is to estimate and validate the closed loop properties of a non-linear induction machine drive. In particular, it is of importance to be able to verify the stability margins of the system. First, a linear approximate transfer function model of the system is identitied from experimental data. The remaining model errors are mainly due to non-linear dynamics and distortion. In a second step, the gain of the nonlinear error system is estimated. Robust stability can then be analyzed by combining the small gain theorem by a stability test of the linear model. The approach taken is inspired by the work (Schoukens et al., 2002), on identitication of the stability of feedback systems in the presence of non linear distortions. The problem at hand addresses several of the challenges of system identification for control. The system is highly nonlinear and dependent of the operating conditions. The stability problem is nontrivial, and has large practical implications. The approach is evaluated on a hardware/software simulation platform.